Preheat the oven to 350 degrees(F).
In a small bowl, make the topping. Toss the cracker crumbs, vegan cheese, and spices together. Pour the melted butter over the crumbs and toss again. Set aside.
Now, start the casserole in a large pot. Heat the vegan butter on medium high. Once it has melted, add the garlic.
Sauté for 1-2 minutes. Then pour in the flour and stir to combine the butter and flour. Making a paste(roux).
Let the roux cook for 1-2 minutes. Then pour in the non-dairy milk. Whisk to combine, making sure there are no lumps of flour left.
Bring to a simmer, reduce heat to medium low and let simmer until it thickens. Whisking frequently. About 5 minutes.
Season with a pinch of salt and pepper and the nutmeg. Whisk.
Then pour the vegetable broth into the pot and whisk again.
Bring back to a simmer, then add the vegan cheese. Whisk frequently until the cheese has melted into the sauce and it is nice and thick.
Taste and adjust seasonings, adding more salt and pepper if needed.
Pour the broccoli florets into the pot and toss to thoroughly combine the broccoli with the sauce.
Pour the broccoli and all the sauce into a 13x9 inch baking dish. Smooth out evenly.
Bake for 15 minutes. Remove the baking dish from the oven and sprinkle the cracker topping evenly over the top. Bake for another 15-20 minutes or until the casserole is golden brown and the broccoli is tender.
It will still look a little liquidy, but will thicken as you let it cool for a few minutes.
Let it cool for about 5 minutes. Then serve!